Study: Climate change impacts river floods11/08/17Environment
According to a new study, climate change has had a significant impact on the timing of river floods across Europe over the past 50 years.
In some regions, such as southern England, floods are now occurring 15 days earlier than they did half a century ago.
However, the changes aren’t uniform, with rivers around the North Sea seeing floods delayed by around eight days.
Floods caused by rivers impact more people than any other natural hazard, and the estimated global damages run to over €85bn a year.
Researchers have long predicted that climate change would have direct impacts on these events but until now the evidence has been difficult to establish.
Floods are affected by many different factors in addition to rainfall, such as the amount of moisture already in the soil.
This new study looks at this issue in some depth, by creating a Europe-wide database of observations from 4,262 hydrometric stations in 38 countries, dating back to 1960.
The analysis found that the most consistent changes were in northeastern Europe around Scandinavia, where earlier snow melt due to warmer temperatures led to earlier spring floods.
Around 50% of monitoring stations are seeing floods eight days earlier than they did 50 years ago.
The principal changes are seen along the western edge of Europe, from Portugal up to southern England. Half the stations recorded floods at least 15 days earlier than previously. A quarter of the stations saw flooding more than 36 days earlier than in 1960.
“It’s the interplay between extreme rainfall and the abundance of rainfall,” lead author Professor Günter Blöschl, from the Technical University of Vienna, Austria, said.
“In southern England, it has been raining more, longer and more intensely than in the past. This has created a rising groundwater table and higher soil moisture than usual and, combined with intense rainfall, this produces earlier river floods.”
Blöschl says that this study shows clear evidence of the impact of human-induced climate change in many regions – but there are still some areas of uncertainty.
The study has been published in the journal Science.